Recent years have witnessed the growing importance of secondary batteries, such as lithium ion batteries and nickel-hydride batteries, as vehicle-mounted power sources, and as power sources that are provided in, for instance, personal computers and portable terminals. In particular, lithium secondary batteries that are lightweight and afford high energy density are expected to come to be used as preferred high-output power sources that are installed in vehicles. In a typical configuration, such secondary batteries are provided with electrodes wherein a material that is capable of reversibly storing and releasing lithium ions (electrode active material) is held on a conductive member (electrode collector). Representative examples of electrode active materials that are used in negative electrodes (negative electrode active materials) include, for instance, carbon-based materials such as graphite carbon or amorphous carbon. Representative examples of electrode collectors that are used in negative electrodes (negative electrode collectors) include, for instance, sheet-shaped and foil-like members having copper or a copper alloy as a main constituent.
A representative method of causing a negative electrode active material to be held on a negative electrode collector during the production of a negative electrode having such a configuration may be a method that involves coating a negative electrode collector (copper foil or the like) with an active material layer forming paste in which a binder and a powder of a negative electrode active material are dispersed in an appropriate medium, and drying the whole through passage through a hot-air drier or the like, to form thereby a layer (negative electrode active material layer) that comprises the negative electrode active material. The binder that is comprised in the negative electrode active material layer has the function of binding negative electrode active material particles with one another and binding the negative electrode active material and the collector. Patent Literature 1 to 6 are examples of prior art literature pertaining to such binders and the like.